What's in YOUR placebo?

5 November 2010

Placebos are everywhere in medical research, but its hard to tell if the placebos in one study are the same as those used in another study. In a new research report, a team of investigators, including STS philosopher of medicine, Dr Jeremy Howick, shows the extent of non-description about placebos. This raises concerns because, the authors write, “No substances are known to be physiologically inert, and no regulations guide placebo composition, which can influence study results.”

The lack of clarity about placebos can lead to confusion when comparing the results of therapeutic research. Placebos provide the baseline. If the baseline shifts with different studies, then it’s hard to judge the relative effectiveness of therapies.

Elaborating on their findings, Jeremy explained the problem. "Perhaps due to the mistaken assumption that placebos are ‘inactive’, the ingredients of placebos are rarely divulged in any detail. Failure to adequately describe placebos leads to three problems for placebo controlled trials: (1) they are difficult to appraise for internal validity, (2) they are difficult to replicate, and (3) they compromise cross-trial comparisons of effectiveness. This problem impacts directly on routine clinical practice since failure to list placebo ingredients undermines the perceived benefit of ‘active’ drugs."

Their research shows the extent of non-description about placebos. The authors propose a reporting scheme for placebos and conclude that silence, in this case, is far from golden. Researchers should declare the ingredients of their placebos.

Paper:

What's in Placebos: Who Knows? Analysis of Randomized, Controlled Trials